Security systems may be used to ensure the safety of important sites, for example, to prevent a place from being intruded, detect security accidents and allow an event trace. A security system mainly includes a video surveillance system, an alarm control system, and an access control system. These systems are independent from each other, but they may mutually communicate.
The video surveillance system is used for surveillance and video-taping, and the alarm system may output, in real time, an abnormality thereof and the observation of a front-end device. In a conventional security system, surveillance is typically solely based on videos or sensor data, and may thus have poor surveillance performance. In order to provide surveillance of better performance, technicians combine the video-based surveillance with the sensor-based surveillance, i.e., use a camera to capture images of a region under surveillance of sensors.
However, an existing video-based surveillance system only obtains a video of a region that is being under surveillance, and may thus fail to give a timely alarm of an event of illegality. Although such an event of illegality may be later known from a captured video, it may not be dealt with in time as the violator may have left the site.